RU150877U1 - GAS STORAGE SYSTEM FOR GAS FUEL - Google Patents

Abstract

1. Gas storage system for gaseous fuel (A), containing a container (2) for storage, which has a variable storage volume (3) for receiving and removing fuel (A), while a compression device (6) is provided, which contains a partition (7), which can be subjected on one side to the storage pressure (P) of the injected fuel (A), and is configured to increase the storage pressure (P) inside the storage volume (3), which decreases when the fuel (A) introduced into the volume (3) storage, characterized in that the compression device (6) can be preloaded by introducing fuel (A) into the storage volume (3), and the partition (7) is configured to create a force (R) in response to pressure (P) storage, while the storage volume (3) can be changed by preloading and / or unloading the compression device (6). The gas storage system according to claim 1, in which the dividing baffle (7) is made in a certain area or areas in the form of an elastic diaphragm, wherein the compression device (6) can be preloaded by elastic changing the shape of the diaphragm when fuel (A) is injected. ... The gas storage system according to claim 1 or 2, in which the dividing wall (7) is connected to the spring element (8), the spring element can be preloaded by changing the position of the dividing wall (7) when fuel (A) is introduced.

Description

FIELD OF TECHNOLOGY TO WHICH A USEFUL MODEL IS

The present utility model relates to a gas storage system for gas fuel, in particular fuel for motor vehicles, and to a method for operating this type of gas storage system for gas fuel.

BACKGROUND

Vehicles with gas internal combustion engines, for example, include the use of liquefied petroleum gas (LPG), liquefied natural gas (LNG), compressed natural gas (CNG) or hydrogen (H2). Compared to liquid fuels, gaseous fuels, especially CNG and H2, usually have the problem of extremely low bulk energy density. Since the space available for transporting fuel is furthermore subject to volume restrictions, therefore, the result is a limited and generally relatively small power reserve for gas-powered vehicles.

Moreover, the low energy density of the fuel in gaseous form requires a correspondingly large volume flow in the cylinder of the internal combustion engine. This, in turn, requires inlet nozzles with very large cross-sections of the hole, long inlet times and high gas pressures in order to achieve the required volumetric flow. However, the possible cross-sectional areas of the openings and the times for allowing gas into the cylinder are limited.

In particular, in combination with direct injection (DI), the maximum dimensions of the inlet nozzles are already determined by the remaining installation space. Here, any increase in the outer diameter of the inlet nozzles also has an effect on the maximum cross section of its opening. The maximum throughput for volumetric flow rate would be limited by the maximum achievable cross-section of the hole, which is determined not only by the stroke of the nozzle valve, but also directly by the maximum inner diameter, and hence the maximum outer diameter of the nozzle. The outer diameter of the nozzle is strictly limited by the size and geometry of the combustion chamber required by the cross sections of the charge change valves and the space for installation for the spark plug. The traditional outside diameters for the nozzle tip range from 7.0 to 8.0. Moreover, the minimum nozzle cross-section should not be so large that the dosing of the minimum quantity — as required during idle — no longer works reliably.

Another way to achieve the largest possible cross section of the hole is to maximize the stroke of the nozzle needle, although this is limited by the dynamic response of the drive used. The maximum stroke of the nozzle needle inside the inlet nozzle is highly dependent on the excitation technology used for this purpose. Additional limitations are the result of achievable opening and closing times for the intake nozzles. Thus, the possibilities to achieve the desired volumetric flow rate by increasing the surface area of the nozzles are very limited.

Closing times are especially significant in the case of supercharged and direct injection internal combustion engines. These may be internal combustion engines subjected to pressurization, for example, by means of a turbocharger or compressor. With these engines, it is useful to minimize emissions, for example, not to inject before the intake valve is closed, at full load at low engine speeds. To such an extent, here you can initially use the already compressed state of gas fuel. If the injection was performed before closing the intake valve, the gas fuel would have to expand back to the desired boost pressure, which usually has an absolute value of about 1.0 to 2.5 bar. In such a case, renewed compression would have to be carried out by means of a boost system. This would lead to increased demand for boost pressure. Moreover, the benefits of direct injection would be nullified, and the internal combustion engine would behave like a central injection system (PFI = fuel injection into the inlet), as regards its boost pressure performance. The result would be significant torque loss at low rotational speeds.

The late-manifested requirement for injection provides an opportunity for only a very limited interval for injection, especially at high engine speeds, since the injection time decreases in proportion to the increase in engine speed. In the case of the requirement of full load also at low engine speeds, the intervals for injection are very limited, since injection before closing the intake would lead to very high emissions of unburned fuel in the case of engines with a turbocharger that operate with distribution phases that cause a large overlap of valves in this range. Reducing the overlap of charge replacement valves to provide an extended time interval for injection leads to a significant drop in torque when operating at full load at low engine speeds.

To increase fuel flow, the latter approach is to increase gas pressure. Known naturally aspirated CNG engines operate at a gas pressure of between about 3.0 and 5.0 bar (absolute value). In contrast, more advanced modern turbocharged engines require gas pressures up to about 7.0 to 9.0 bar. To achieve this, the gas pressure prevailing in the gas tanks is limited to the correspondingly required operating pressure. When full, the gas pressure in the CNG tanks is about 200 bar (at 15 ° C), while in the case of gas tanks for hydrogen-powered vehicles, it has a value of up to 700 bar.

To reduce injection times, the working gas pressure for operation would have to be further increased. In this context, however, the gas tanks used cannot expand beyond the currently applied gas pressure levels. Future CNG engines will create greater demands on the required operating pressure, which will range from 10 to 30 bar (in absolute value). As a result, the power reserve of a vehicle operating in such a manner, which should be considered critical in any case, will be further reduced.

EP 1333168 A1 (publ. 06.08.2003, IPC F02B 43/00, F02D 19/02, F02D 41/00) discloses an optimized method of operation of a four-stroke internal combustion engine that is powered by natural gas. To achieve this, in the upper partial load range and in the full load range, natural gas is injected directly into the engine cylinder at the end of the intake stroke or at the beginning of the compression stroke. Injection should occur in the range of crank angle of rotation of 210 ° and 90 ° to top dead center in order to improve engine efficiency without increasing the pressure of the gas supplied from the gas tank.

DE 102006048498 A1 (publ. 17.04.2008, IPC F02D 19/02, F02D 45/00, F02M 21/04) shows a gas-fired internal combustion engine in which gas fuel is injected into the combustion chamber of a cylinder of an internal combustion engine in a conventional manner. For this purpose, at least one nozzle is provided through which gas from the gas tank is introduced into the combustion chamber. Here, the gas pressure acting on the nozzle approximately corresponds to the pressure in the gas tank.

US 5,454,408 A (publ. 03/10/1995, IPC F04B 9/117, F17B 1/26, F17C 13/02) discloses a storage and delivery system for compressed natural gas (CNG), which is selected as the closest analogue to the claimed useful models. This has a variable volume, which can vary depending on the internal pressure. To this end, at least one tank for CNG is divided into two areas that are separated from each other by an impenetrable boundary surface. In order to compensate for the pressure drop in the gas region of the tank while the gas is being taken, the hydraulic fluid may be pumped into the region of the fluid. Thus, the refueling pressure is higher than the internal pressure of the gas tank to be refueled, can be maintained or generated, for example, to refuel a gas-powered vehicle.

US 5,253,682 A (publ. 10/19/1993, IPC F04B 9/107, F04B 9/117, F17C 5/06) similarly disclosed a device for dispensing gas, which has many gas cylinders. Gas cylinders are used to transport gas and have a gas tank and a water tank, which is separated from the gas tank by a piston. After the gas cylinder has been filled with gas, the water tank on the opposite side can be filled with water to move the piston in the direction of the gas tank.

US 5,868,122 A (publ. 09.02.1999, IPC F02M 21/02) discloses a device for supplying gas fuel, in particular CNG, for an internal combustion engine of a vehicle with a reverse cascade arrangement. The device serves to supply gas to the internal combustion engine under high pressure. To this end, a plurality of storage containers 2, 4, 6, 8 are provided, a high pressure accumulator 10, an intermediate accumulator 12, and a plurality of valves V1, V2, V3, V4. The internal combustion engine 56 is powered by gas via a high pressure accumulator 10, wherein the high pressure accumulator is connected to storage containers. As soon as the pressure inside the high-pressure accumulator drops below a predetermined value, it again rises by means of the intensifier 24. The intensifier is driven by the pump 26, while the intensifier is powered by gas through storage containers.

ESSENCE OF A USEFUL MODEL

Systems for increasing gas pressure, which are known in the prior art, all use devices that provide at least indirect connection with an internal combustion engine, which must be driven. As a result, the energy required to energize these energy-boosting systems ultimately disappears from the energy balance of the engine that is supposed to work. This, in particular, leads to an increase in fuel consumption.

Based on the prior art, the underlying objective of this utility model is to provide a gas storage system for gas fuels and a method for operating a gas storage system of this type by which the storage pressure, which otherwise would decrease when the gas fuel is removed, increases to improve the energy balance of the internal combustion engine, which should work.

This problem is solved by a gas storage system for gas fuel, having the characteristics of paragraph 1 of the utility model formula, and by the method of operation of this type of gas storage system. In addition, particularly useful embodiments are disclosed by the corresponding dependent claims of the utility model.

It should be noted that the features presented separately in the following description can be combined in a technically significant way and give rise to additional options for implementing the utility model. The description further characterizes and details the utility model, in particular, together with the figures.

According to a utility model, a gas storage system comprises a storage container that has a variable storage volume for receiving and discharging gas fuel. The storage container may also be referred to as a gas tank, which must be made in accordance with the internal pressure of the gas fuel, which must be stored in it, which must be restrained. Of course, any temperature fluctuations must also be taken into account simultaneously. These can lead to a change in volume, and hence, to an additional load on the storage container. Moreover, the relevant safety rules for such storage containers must be followed.

As a particularly preferred option, the gas storage system is a mobile system. In other words, the gas storage system can preferably be mounted on or in a vehicle associated with an internal combustion engine that is to be operated. Moreover, the gas storage system is also suitable for stationary applications, for example, in connection with the storage of gas fuel, for the fixed installation of a gas tank or gas station.

A compression device is furthermore provided in connection with a gas storage system according to a utility model. A compression device is provided and accordingly configured to increase the storage pressure inside the storage volume, which pressure decreases during the removal of fuel introduced into the storage volume. As already explained above, the storage pressure inside the storage volume usually decreases as an increasing amount of gas fuel is withdrawn. The compression device serves to provide a sufficiently high fuel pressure to produce the required volumetric flow, even when the storage volume is emptied more and more.

The compression device has a dividing wall, which may be subjected, on one side, to the storage pressure of the introduced fuel. On one side, this partition wall is in extended surface contact, in at least some region or regions, with the introduced gas fuel.

The partition wall thus advantageously serves to enable real preloading of the compression device. To achieve this, the compression device can be made in the form of an appropriate storage device for potential energy through a dividing wall. Here, the indicated energy is supplied by means of compressed gas fuel and is accumulated during refueling of the storage volume.

According to a utility model, the compression device is designed so that it can be preloaded by introducing gas fuel into the storage volume of the storage container. The dividing wall is made to create a reaction force to the storage pressure. The variable storage volume provides the ability to change the volume available for storing gas fuel. According to a utility model, the storage volume can be changed by preloading and / or unloading the compression device.

A particular advantage here is the design of the compression device. According to a utility model, this provides a storage device for potential energy. Here, it acts as a mechanical energy storage device, which, after preloading, does not require any additional energy for the necessary increase in pressure within the storage volume. Consequently, the accumulated energy present during refueling of the storage volume is used to preload the compression device by the gas fuel itself. This is possible because fuel is introduced at a pressure level above the maximum storage pressure. Said pressure energy is used, at least in part, for pre-loading the compression device during refueling.

Thus, the required increase in pressure, respectively, is not created exclusively actively during operation of the internal combustion engine, but passively is the result of a compression device previously loaded in this way. The result is a significantly better energy balance for an internal combustion engine. On the other hand, the specified engine can operate for a longer period with an appropriate pressure, for example, by means of gas fuel that is transported. On the other hand, the compression device, pre-loaded in advance, does not require any energy to achieve the necessary pressure increase, which would impose an additional load on the internal combustion engine.

A variable embodiment of the storage volume requires the compression device to be located inside the storage container. Thus, in the case where a dividing wall is provided, such can be located inside the storage container in order to constructively separate the compression device from the storage volume.

The extremely compact design of the gas reservoir is advantageously ensured thereby. This is due to the fact that, only outside, the gas storage system is formed by the storage container, while the desired compression device is located inside the storage container. Moreover, this makes it possible to use a storage container, which is present in any case and also adapted to the relevant requirements for the location of the compression device. In addition to the resulting protection of the compression device, for example, it also makes it possible to assemble a spring element or an enclosed shock absorber of compressible fluid between the dividing wall and the wall of the storage container.

A preferred improvement of this dividing wall provides that it is made in at least some area or areas as an elastic diaphragm. Thus, said dividing wall may have at least one elastic partial region, which gives a corresponding result in response to the pressure applied by the gas fuel when the latter is introduced. Here, the necessary displacement of this partial region occurs against its corresponding restoring forces. In general, the compression device can thus be preloaded by resiliently changing the shape of the diaphragm when introducing gas fuel.

An advantage of this embodiment is its extremely simple construction, since all that is required for this purpose is a dividing wall as an elastic diaphragm in at least a partial region. The required restoring forces of the specified diaphragm can be set by means of the corresponding material properties and setting its dimensions. The diaphragm, for example, is a surface at least under a biaxial mechanical load, which simultaneously acts as a separation layer relative to gas fuel. Its implementation as an elastic diaphragm, moreover, means that no additional sealing measures are required to preserve gas fuel inside the storage volume.

In yet another useful embodiment, the partition wall may be attached to the spring element. This embodiment can be used as an alternative to the elastic diaphragm described above, or as a complement to it. In principle, the dividing wall may be loaded by the spring force of the spring element, which provides a mechanical energy storage device. Thus, the spring element can be preloaded by changing the position of the dividing wall during fuel injection.

In the context of a utility model, a change in the position of the dividing wall is considered essentially as if it were the result of its complete displacement or the result of elastic deformation of its partial regions.

Thus, for example, it is possible that the dividing wall was made as a rigid element, the position of which is variable. It can be made in the form of a piston, which can move relative to a partial region of the compression device. Here, mobility occurs both due to the spring force of the spring element, and due to the storage pressure of gas fuel. The direction of the respective movement depends on whether it is a fueling operation or a gas fuel removal operation that is currently taking place.

When filling the storage volume, the spring element is mechanically loaded in accordance with the pressure with which gas fuel is introduced into the storage volume. The surface of the partition wall, which must be subjected to storage pressure, must be dimensioned so that the force resulting from surface pressure or mechanical stress during refueling is sufficient to preload the spring element. On the contrary, the dynamic stiffness of the spring element must be endowed with dimensions in such a way that this is sufficient to create the necessary pressure during the removal of gas fuel.

The almost unlimited course of the dividing wall, thereby, is made predominantly possible. Under the condition of a hard embodiment of the separation wall, it can be considered as independent of any elastic properties. Thus, even a small surface subjected to storage pressure is sufficient to allow high compression of gas fuel with a corresponding increase in pressure over a sufficiently long stroke.

In principle, the dividing wall can be implemented in such a way that its characteristics as a mechanical energy storage device can only be attracted when required. Thus, for example, a change in shape and / or a change in the position of the dividing wall when refueling the storage volume can be fixed in such a way that the preliminary loading of the compression device thus created is initially supported. Thus, the introduced gas fuel is not continuously subjected to mechanical stress by the restoring force of the partition wall. Thus, the increase in pressure within the storage volume resulting from the restoring forces of the dividing wall will be controlled in a controlled manner. This, for example, can occur when a predetermined value for the desired storage pressure is unreadable.

Moreover, the dividing wall may also move against a compressible fluid that acts on the dividing wall in the form of an enclosed shock absorber from the side opposite to the gas fuel. Moreover, in cases where the dividing wall is made in the form of a movable piston, any gear ratio can be provided. The ratio in this case is realized by means of surfaces of different sizes, which are subjected, respectively, to the storage pressure of gas fuel or the above shock absorber.

In the context of a utility model, a compression device, for example, may be located outside the storage container. In this case, it is attached to the storage container so that the storage pressure prevailing in the storage volume of the storage container is also applied to the compression device. The resulting advantage can be considered as the full use of the storage container as the storage volume.

The subject of this utility model shows a gas storage system for gas fuel, through which, despite the improvement of the energy balance of the internal combustion engine, which should work, the storage pressure, which otherwise would decrease with the removal of gas fuel, rises. To this end, the excess energy present during refueling is particularly useful in the form of pressure for pre-loading the compression device. Without any additional energy consumption, then the pressure-boosting action of the compression device can be used. Thus, it is possible to bring any part of the gas fuel that is still present in the storage volume to a sufficiently high pressure level to be supplied to the internal combustion engine. As a result, the power reserve of a vehicle operating in this way is greatly increased.

The methodological part of the utility model, moreover, shows a method that is used to operate the gas storage system described above for gas fuel. To this end, the gas storage system has a variable storage volume for receiving and removing fuel. Moreover, a compression device is provided by which the storage pressure inside the storage volume, which decreases as the gas fuel introduced into the storage volume is removed, can increase when required. In this case, the compression device has a dividing wall, which may be subjected, on one side, to the storage pressure of the introduced fuel.

According to a utility model, the compression device may be preloaded by introducing fuel into the storage volume. Here, the reaction force to the storage pressure can be generated by means of a dividing wall. Thus, the storage volume can advantageously vary by preloading and / or unloading the compression device.

According to another advantageous measure, it is provided that the dividing wall is made in at least some region or regions in the form of an elastic diaphragm, allowing the compression device to be preloaded by resiliently changing the shape of the diaphragm during fuel injection.

As an additional or alternative useful measure, a dividing wall may be attached to the spring element. The specified spring element, in this case, can be preloaded by changing the position of the dividing walls when introducing fuel.

The benefits resulting from the above measures have already been adequately described above in the context of the essence of this utility model, and therefore, at the moment, attention has been drawn to these formulations.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional useful details and utility model results are explained in more detail below by means of two illustrative embodiments shown in the following figures, of which:

FIG. 1 shows a schematic longitudinal section of a gas storage system according to a utility model for gas fuel, and

FIG. 2 shows an alternative embodiment of a gas storage system according to the utility model for gas fuel of FIG. 1, illustrated in an identical manner.

DESCRIPTION OF PREFERRED EMBODIMENTS FOR USING THE USEFUL MODEL

FIG. 1 is a schematic illustration of a gas storage system 1 according to a utility model for gas fuel A. The gas storage system 1 comprises a storage container 2, which, in this case, is shown in longitudinal section of a gas storage system 1. With reference to the illustration of FIG. 1, the storage container 2 has a storage volume 3 located on the left in its inner part. The storage volume 3 is for receiving and discharging gas fuel A. In this case, gas fuel A is indicated inside the storage volume 3.

The storage container 2 has an inlet nozzle 4 and an outlet nozzle 5. Both nozzles 4, 5 are arranged to pass through the wall of the storage container 2, and they attach the storage volume 3 to the external environment (not shown in detail). This is a gas fuel station that passes into the storage volume through the inlet nozzle 4. In this case, it also includes an internal combustion engine (not shown in detail). The latter is powered by gas fuel A through the exhaust nozzle 5.

Moreover, a compression device 6 is provided and, in this case, is located inside the storage container 2. The compression device 6 is configured to increase the storage pressure P inside the storage volume 3, this pressure decreases as the gas fuel A introduced into the storage volume 3 is removed. To this end, the compression device 6 has a dividing wall 7, which can be moved relative to the storage container 2, and which is preloaded on one side by the gas fuel storage pressure P A. Thus, the available storage volume 3 is limited by the partial wall area of the container 2 for storage and dividing walls. Therefore, the storage volume 3 is variable, the storage volume 3 can be changed by preloading and / or unloading the compression device 6.

The spring element 8 is located on the side of the separation partition 7 facing away from the gas fuel A. In this case, the spring element 8 extends between the specified side of the separation partition 7 and the wall portion of the storage container 2 in the area of the compression device 6. This gives the compression device 6 the ability to preload by introducing fuel A into storage volume 3. The reason for this is to increase the storage pressure P as the storage volume 3 is filled with gas fuel A, the specified pressure acts on the side of the dividing wall 7. The location of the spring element 8 means that the dividing wall 7 is configured to create a reaction force R, in in the form of back pressure, on the storage pressure P, the indicated reaction force is the result of the spring element 8, which, in this case, is compressed.

In an alternative embodiment, the gas storage system 1 of FIG. 1 can be seen in FIG. 2. To obtain a compression device 6, the dividing wall 7 here is made as an elastic diaphragm in at least some area or areas. In this case, therefore, there is no additional spring element 8, and the alternative compression device 6 can thus be preloaded by resiliently changing the shape of the dividing wall 7, made as a diaphragm, when introducing fuel A. By resiliently changing the shape of the dividing wall 7, made as a diaphragm, similarly, it is possible to create a reaction force R, which is the result of the restoring forces of the elastic diaphragm.

LIST OF REFERENCE POSITIONS

1 gas storage system

2 Container for system storage 1

3 Storage capacity of container 2

4 Intake nozzle in container 2

5 Discharge nozzle in container 2

6 Compression device

7 Device partition 6

8 Spring element of the device 6

A Fuel, gas

P Storage pressure 3

R Reaction force

Claims (3)

1. A gas storage system for gas fuel (A), comprising a storage container (2) that has a variable storage volume (3) for receiving and removing fuel (A), wherein a compression device (6) is provided that comprises a dividing wall (7) which can be stored on one side with the storage pressure (P) of the introduced fuel (A), and is configured to increase the storage pressure (P) inside the storage volume (3), which decreases with the removal of the fuel (A) introduced into the volume (3) storage, characterized in that the compression device (6) can be preloaded by introducing the fuel (A) into the storage volume (3), and the partition wall (7) is configured to create a reaction force (R) to the storage pressure (P), while the volume (3) storage can be changed by preloading and / or unloading the compression device (6). 2. The gas storage system according to claim 1, in which the dividing wall (7) is made in some area or areas in the form of an elastic diaphragm, while the compression device (6) can be preloaded by elastic changes in the shape of the diaphragm during fuel injection (A) . 3. The gas storage system according to claim 1 or 2, in which the dividing wall (7) is attached to the spring element (8), while the spring element can be preloaded by changing the position of the dividing wall (7) during fuel injection (A).

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